Project Summary/Abstract The goal of this administrative supplement request is to provide a state-of-the-art circular dichroism spectrophotometer for biophysical studies on mitochondrial fission proteins for R01GM067180. Altered mitochondrial fission has severe consequences even death. Yet the reasons for this are unknown. It is postulated that the mitochondria have their own lifecycle that involves fission of unhealthy mitochondria to remove them. In this model, the proper balance of fission is critical: either excess or impaired fission both result in unhealthy mitochondria. This model is compelling because it explains how alterations in fission can cause or contribute to many fundamentally different diseases including recovery from heart attack and stroke, increased metabolic stress from diabetes, normal aging, and neurodegenerative diseases such as Parkinson's and Alzheimer's disease. To understand the protein-protein interactions that govern this, biochemical and structural studies have identified mutations that will be measured for altered folding and thermodynamic stability using the requested instrumentation. A better understanding of the protein machinery and how it works will identify key points of regulation that may be targeted with small molecules to inhibit, and activate, fission. The discovery of such molecules may ultimately lead to treatments for diseases in which enhanced, or impaired, fission is central.